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Saturday, March 20, 2010

Mar 20: Monday Night Storm Update

Weekend ForecastTemperatures are quickly warming up across the area, and are expected to peak in the lower to mid 70s, except for the immediate coast that should stay in the 60s. Parts of the New York City area should also reach the upper 70s, which is very warm for this time of the year.

Tonight will have low temperatures generally in the 40s and a few lower 50s. Tomorrow will be partly sunny with high temperatures still warm but not as warm as today, in the upper 60s to the lower 70s.

Heavy Rain Returns Monday NightAfter nearly a week of dry weather, rain is expected to return on Monday. While only light rain falls during the day, especially in the afternoon hours, the rain is expected to become heavy at times on Monday night. The rain will continue until Tuesday morning before ending across the area. There is still some uncertainty about where the heaviest rain falls, as some models show it for the NYC metro and Long Island, while others show it well north and west of New York City, though it is likely that rainfall amounts will be over 1/2 inch across the area, and rainfall amounts over 1 inch are also a good possibility.

Below is my first rain map for this storm, which also includes a wide potential 1+ inch area, as its exact location is still uncertain. This storm should be a warm storm, with the only place seeing light snow at the end being northern Maine.

Next Weekend Potential Storm, Colder Conditions PossibleAnother storm is possible next weekend, however one factor that makes it slightly harder to forecast is that there is a lot of cold air involved in this time period. The worst of the cold air should stay north of the area, which should also be blocked at first from affecting the area due to a potential storm next weekend. At this time, the GFS and DGEX models show a weak storm in this time frame which is suppressed due to the cold air, however it is still too warm for snow in the area, possibly except the far north and western parts. After the storm exits, the GFS brings in some of the cold air, however it does not bring the worst of the cold towards the area, which is what is needed by this time of the year for much more than light snow showers in the NYC metro.

At this time, while there is still uncertainty on whether there is a storm or not, and what track it would take if there is a storm, if at least some of the cold reaches the area, similar to what the GFS showed, then snow showers might be possible in the higher elevations north and west of New York City. Otherwise, rain is possible next weekend, followed by slightly below average temperatures.

Afternoon Update: The latest GFS run once again brought cold conditions and snow to the Mid Atlantic. The pattern is not supportive of such a cold spell happening, and in years that the pattern was much more supportive of cold and even some snow, it was much more supportive of that happening than it is now. I would expect the models to eventually correct themselves and reduce the amount of cold shown, where we end up with average to slightly below average temperatures, not up to 10 degrees below average as some models showed.

Appropriate and subject relevant comments are welcome. Comments that are non-weather related or contain arguments with no legitimate reasoning to back up their claims are not tolerated and will be moderated and deleted.